Ramona Turner, Street Smarts: Delving into the science behind the dangers of cellphone use while driving

Recently, Street Smarts received a letter from a reader who wanted to spread the word about the dangers of tailgating and, more specifically, driving while texting and/or talking on cellphones - even while using hands-free capabilities.

You see, she herself caused a collision when she was talking hands-free on her cellphone and didn't notice the green light up ahead had turned red. Upon entering the intersection, she was immediately T-boned by another vehicle. Neither party was hurt.

Street Smarts turned to Chris Cochran, spokesman for the California Office of Traffic Safety for the science behind the dangers of distracted driving. Below are some of his key points. Read his entire essay, uncut, on the Street Smarts blog, www.santacruzlive.com/blogs/streetsmarts.

The danger factor between hands-free and handheld cellphone use while driving is basically the same, he said.

It's the act of talking on a cellphone - the conversation itself - that makes cellphone use while behind the wheel the dangerous distraction, according to a recent study from Carnegie Mellon University, cited Cochran.

"It showed that up to 37 percent of the brain function needed for the complicated task of safely driving a car is apt to be shunted over to the task of carrying on a cellphone conversation," he said. "You are now driving with less than 2/3 of your brain power."

This reduced focus on the road can be referred to as a cognitive disconnect, also known as inattention blindness. That means that while the eyes see things on the road, the brain power needed to process that information is interrupted by the distraction, he said.

"As in the case of your reader, the eyes see the red light, but the brain doesn't. Why not?," he asked. "The cellphone conversation is using that part of the brain that is needed to perceive the importance of a red light in front of a moving car."

Talking on a cellphone versus chatting with passengers in the car is different because the people in the car are going to see things before the driver does and help out. However, the person on the other end of the line is just as engrossed in the conversation as the driver is.

"And since they are not reacting to anything but the conversation, the driver doesn't either," said Cochran.

While hands-free cellphone use is not illegal, the Office of Traffic Safety's "constant message is to not engage in any form of mobile device use while driving," he continued. "No hand-held talking, no texting, also no Bluetooth, no speaker phone, no built-in dashboard integrated voice-activated devices. It's all distracting."

As for tailgating, the reader, who had never been in a collision prior to this one, said motorists who follow too closely, especially while driving distracted, risk rear-ending the vehicle up ahead should it stop unexpectedly.

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